Logical Reasoning

PT108 · S2 · Q20 One of the most important

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One of the most important events for modern astronomy was the series of collisions, during a single week in 1994, of more than a dozen large objects with Jupiter.

Conclusion

None of the comet's fragments penetrated to Jupiter's lower atmosphere. The comet was composed of rock rather than ice.

Evidence

During a week in 1994, over a dozen large objects, these once formed most of the comet Shoemaker-Levy 9, collided with Jupiter. The collision resulted in formations showing no signs of water.

Evaluate

The argument is saying, Let's unpack this. The argument assumes that if there were any water, it would have been noticeable and that no water indicates a rocky composition. Think about two possible objections:

What if fragments reaching Jupiter's lower atmosphere could escape detection in some other way?

What if the comet fragments were icy but didn’t show water for another reason?

Goal

Our task is to identify an assumption that supports the reasoning that no water in the formations implies the fragments didn't reach the lower atmosphere, and hence the comet was rocky.

20.

Which one of the following is an assumption on which the argument depends?

  1. Comets tend to be composed

    Comets vs. Asteroids Composition:

    While this could provide context about typical comet composition, it doesn't directly support the argument that no water equals no deep penetration and that the comet was rocky. It doesn't address the specific link forged by seeing no water.

    2% picked this

  2. Correct

    If Jupiter's lower atmosphere had

    Why this is right

    The assumption that if Jupiter's lower atmosphere had been penetrated by the comet's fragments, the resulting formations would show signs of water is a critical link in the argument. Without this, the absence of water doesn't necessarily prove that the fragments didn't reach Jupiter's lower atmosphere. If you negate this option and say that even if the fragments penetrated the lower atmosphere there wouldn’t necessarily be evident water signs, then the argument weakens significantly, because the presence of water in formations is an indicator used to determine journey depth.

    Skill tested: Necessary Assumption · how this choice captures the argument's function is the move to repeat next time.

    89% picked this

  3. A larger explosion would occur

    Explosion

    Larger for Rock: This doesn't directly relate to how formations without water imply that the comet was rocky or that the lower atmosphere wasn't penetrated. It’s about explosion size, not water detection.

    2% picked this

  4. The post-collision analysis of Jupiter

    Same Composition Formations:

    Even if all post-collision formations have the same composition, it does nothing to bridge the gap regarding water’s role. It’s not relevant to the water hypothesis.

    7% picked this

  5. The deeper the explosion occurred

    Visibility from Earth:

    This could address detection capabilities, but doesn’t support the specific tie that absence of water aligns with rock composition and non-penetration. It speaks more to observational challenges, not material composition.

    0% picked this

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